There has been a rapid increase in marijuana use during the 1990s, with the most recent generation often smoking marijuana in the form of 'blunts' as opposed to more traditional routes such as in pipes or in cigarette paper. A blunt is made by removing the tobacco from a cigar and replacing it with marijuana (Golub and Johnson, 1999). The cigar wrapper contains tobacco and nicotine, which may interact with the cardiovascular and subjective effects of the marijuana to produce a different set of effects and risks than cigarette paper. Anecdotally, marijuana smokers report that blunts are more potent than joints, yet there have been no controlled studies addressing whether blunts enhance the subjective-effects and health-related consequences of marijuana use. We are proposing to do a within-subject, placebo-controlled study directly comparing the cardiovascular, subjective and pharmacokinetic effects of marijuana smoked in blunts compared to identical quantities of marijuana smoked in cigarette paper. Research volunteers will be current blunt smokers. Each will participate in six, 4-hour outpatient sessions. After baseline data have been collected (heart rate, blood pressure, mood scales, exhaled carbon monoxide, plasma THC and nicotine levels), participants will take 3 puffs, 5 seconds in duration, from a NIDA marijuana cigarette containing 0.0, 1.8 and 3.6% THC or from a blunt containing an equivalent quantity and strength of marijuana. Participants will be blind to the type of marijuana cigarette smoked. We will measure plasma THC and nicotine, subjective mood ratings, and heart rate and blood pressure repeatedly over the course of 180 minutes following smoking. This study is the first controlled investigation of the consequences of this new method of marijuana smoking; the data obtained may be useful in guiding future development of marijuana pharmacotherapy.